Semiconductor integrated circuit device and IC card using the same

Abstract

The present invention enables a power-supply voltage terminal and an internal circuit to be isolated from each other in a noncontact operation without largely increasing a chip area in a semiconductor integrated circuit device for an IC card. A semiconductor integrated circuit device comprises: a first power supply circuit for rectifying and smoothing an AC signal supplied from an antenna to an antenna terminal, thereby obtaining a DC voltage in a first power-supply line; a second power supply circuit comprising a voltage control circuit for controlling gate terminal voltage of a first MOS transistor disposed between a power supply terminal to which power is input from the outside and the first power supply line; a substrate potential control circuit for forming source voltage of the first MOS transistor as a substrate voltage; and a second MOS transistor which makes substrate voltage and gate voltage of the first MOS transistor conductive in the case of using the voltage generated by the first power supply circuit as a power supply, and which makes the substrate voltage and the gate voltage nonconductive in the case of using a power supply from an external terminal.

Description

CLAIM OF PRIORITY[0001]The present application claims priority from Japanese patent application JP 2008-256948 filed on Oct. 2, 2008, the content of which is hereby incorporated by reference into this application.FIELD OF THE INVENTION[0002]The present invention relates to a power supply control technique suitably applied to a semiconductor integrated circuit device or the like mounted on an IC card and, more particularly, to a semiconductor integrated circuit device selectively operated on a power supply voltage generated from an electromagnetic wave received by an antenna provided for an IC card or a power supply voltage supplied from the outside via a contact terminal provided for the IC card, and to an IC card using the semiconductor integrated circuit.BACKGROUND OF THE INVENTION[0003]A contact-type IC card internally having a semiconductor integrated circuit having the functions of a CPU, a memory, and the like and having, on the surface of the card, a contact terminal with the...

AI Technical Summary

Benefits of technology

[0015]Further, to reduce a voltage loss in the power supply switch circuit also in the case where the power supply voltage supplied from the power supply voltage terminal is low, the on resistance of the NMOS transistor has to be reduced by expanding the size of the NMOS transistor or supplying a sufficiently large voltage to the gate terminal of the NMOS transistor. In particular, in the case where the power supply voltage supplied from the power supply voltage terminal is low and power consumption of the internal circuit is large, the influence is large, so that it is difficult to suppress increase in the chip area and the consumption current.

[0016]On the other hand, in the case of forming the power supply switch circuit by PMOS transistors as disclosed in the patent document 2, when the power supply voltage supplied from the power supply voltage terminal becomes low, the gate-source voltage of the PMOS transistors forming the power supply switch also becomes low, so that the voltage loss caused by the power supply switch increases largely. Therefore, it is necessary to increase the transistor size in order to reduce the on resistance of the PMOS transistors forming the power supply switch.

[0017]Further, the power supply switch circuit disclosed in the patent document 2 has to use two PMOS transistors requiring large transistor size in order to interrupt a current path generated via a parasitic diode formed between the drain and source terminals of the PMOS transistors forming the power supply switch circuit and the substrate terminal. Consequently, to reduce a voltage loss caused by the power supply switch circuit in the case where the power supply voltage supplied from the power supply voltage terminal is low, it is necessary to largely increase the size of the PMOS transistor. It is therefore difficult to suppress increase in the chip area.

[0018]An object of the present invention is to provide a circuit technique realizing a function of isolating a power supply voltage terminal and an internal circuit from each other in a noncontact operation without largely increasing the chip area, and capable of supplying a voltage supplied from the power supply voltage terminal to an internal circuit without losing the voltage in the contact operation.

[0030](6) The semiconductor integrated circuit device of (1) may further comprise a pull-down circuit (B5) between the power supply terminal and the ground terminal. The pull-down circuit decreases a resistance value between the power supply terminal and the ground terminal on the basis of detection by the detection circuit, of formation of a power supply based on the AC signal.

Problems solved by technology

Since sufficient voltage is not supplied to the internal power supply line during the period, it becomes difficult to perform a process such as determination of an operation mode and the like, and it takes long time for a chip to start the operation.

In particular, in the case where the power supply voltage supplied from the power supply voltage terminal is low and power consumption of the internal circuit is large, the influence is large, so that it is difficult to suppress increase in the chip area and the consumption current.

It is therefore difficult to suppress increase in the chip area.

Images